Avoiding Heat-Related Illness During Summer

How to stay safe and cool

The summer months are fast approaching, and with that can come the increased risk of heat-related illness (HRI) ranging from heat cramps and exhaustion to heat stroke — especially for athletes. Signs and symptoms include headache, nausea, decreased urination, and in extreme situations can lead to delirium, coma and even death. It’s important for coaches, athletic trainers, parents and professional and recreational athletes to know how to prevent HRI and to have knowledge of the signs and symptoms.

Advertising Policy

Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy


Heat production is generated with physical activity and production of sweat as a cooling mechanism through evaporation. When this thermoregulation is not working properly elevated core body temperature (hyperthermia) can result.


Dehydration is a loss of total body water, leading to decreased blood volume characterized by sodium depletion (hypovolemia). Signs of dehydration include dry lips and tongue, increased thirst, headache, weakness, dizziness, nausea, cramps and dark urine.

Sweating allows dissipation of heat, so replacement of fluids and electrolytes to replenish volume and maintain the cooling mechanism is important. Hypovolemia may lead to reduction in sweat production resulting in a rise in core temperature. Despite adequate fluid replacement, when relative humidity rises above 75 percent, evaporation becomes ineffective, and thermoregulation is compromised.

Advertising Policy

Excessive water consumption can lower the relative sodium content of the blood, causing a condition known as hyponatremia. Signs and symptoms include nausea, vomiting, confusion and headache. It is important to drink according to thirst, and to maintain a state of normal hydration during activity and in the days leading up to activities rather than attempting to replenish fluids at the last minute. Both water and electrolyte replacement may be used during activities.


There are many things we can do to prevent being overheated. Steps include:

  • Limiting sun exposure and exercising in the early morning or evening when it is not as hot and humid and limiting time and intensity
  • Slowly acclimating to warmer climates over about a period of 10 to 14 days. This makes spring/late summer training sessions an important prevention strategy
  • Removing unnecessary clothing and equipment during practice
  • Having adequate fluid and electrolyte replacement throughout the activity
  • Being aware of the signs and symptoms of dehydration.

Heat overload may accumulate over days, so being aware of development of the symptoms noted above is crucial to early detection.

Advertising Policy


Be sure to seek medical attention immediately if the athlete is showing any mental status changes. Cooling and fluid replacement by trained personnel may also be initiated to decrease core body temperature and rehydrate the athlete.

Kim Gladden, MD, is currently a primary care sports medicine fellow at the Cleveland Clinic. Her clinical interests include performing artists and gymnastics as well as general sports and musculoskeletal injuries. To make an appointment with one of our primary care sports physicians, please call 877.440.TEAM.

Advertising Policy